Intelligent materials, structures and structronic (structure + electronic)
Systems can function autonomously in response to the varying environmental and operating conditions [1-4]. This paper describes the application of artificial neural networks as adaptive controllers for elastic waves transformations. The results presented are connected to the modelling of srnart composite materials proposed as an integral, mechanical, neural network and electronic system which has been named as the Matrix Electronic Materials (MEM). A converse piezoelectric effect is used to suppress the amplitudes or to modify the frequency of elastic waves which propagate along the thickness of a laminated metal-ceramic plate when on the front surface of the plate the oscillating pressure is applied. The investigation of such problems relating to the elaboration of smart materials and structures, can be used for diverse technical applications, in particular, for suppression of vibrations and noise.
Theoretical modelling is often overlooked in photosynthesis research even if it can significantly help with understanding of explored system. A new model of light-induced photosynthetic reactions occurring in and around thylakoid membrane is introduced here and used for theoretical modelling of not only the light-induced chlorophyll (Chl) a fluorescence rise (FLR; the O-J-I-P transient), reflecting function of photosystem II (PSII), but also of the 820 nmtransmittance signal (I820), reflecting function of photosystem I (PSI) and plastocyanin (PC), paralleling the FLR. Correctness of the model was verified by successful simulations of the FLR and I820 signal as measured with the control (no treatment) sample but also as measured with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone- (inhibits electron transport in cytochrome b 6/f) and methylviologen- (accepts electrons from iron-sulphur cluster of PSI) treated samples and with the control sample upon different intensities of excitation light. From the simulations performed for the control sample, contribution of the oxidised donor of PSI, P700, and oxidised PC to the I820 signal minimum (reflects maximal accumulations of the two components) was estimated to be 75% and 25%, respectively. Further in silico experiments showed that PC must be reduced in the dark, cyclic electron transport around PSI must be considered in the model and activation of ferredoxin-NADP+-oxidoreductase (FNR) also affects the FLR. Correct simulations of the FLR and I820 signal demonstrate robustness of the model, confirm that the electron transport reactions occurring beyond PSII affect the shape of the FLR, and show usefulness and perspective of theoretical approach in studying of the light-induced photosynthetic reactions.
The methods of multiphase flow dynamics modelling are known. The theoretical calculation of the flow dynamic parameters of multiphase medium is based on the assumption of the mutual interaction between the phases, which becomes essentially manifested if mass concentration of the dispersed phase exceeds the value of 20 %. In many cases this limit seems to be even too high. The results of the experimental investigation of moderate and dense suspension flow confirm that the influence of solid particles on the suspension flow behaviour and the rheological parameters can be significant even for the mass concentration less than 20 %. In this paper the model of multiphase flow, which in based on the joint solution of vector equations of dispesed particle motion in Lagrange coordinates and the equation of continuum in Euilerian coordinates is presented. The method is applied to axially symmetrical flow of incompressible fluid in the rectangular channel and to flow in the zigzag channel. In the case of zigzag channel the numerical scheme is proposed. and Obsahuje seznam literatury
The paper deals with the design of stator channels of the aerator using CFD code ANSYS Fluent. The main problem is to design proper inclination of the channels corresponding with the direction of flow at the impeller outlet. The direction of flow is variable along the channel and represented by the absolute velocity angle. Therefore, this angle is computed first, and according to it, the inclination of stator channels is designed. Numerical simulations are made as single-phase flow for two different shapes of channels and for two different channel incllnations - for already computed ones and for ones used in older type of aerator which this work develops. Stator channels inclined by computed angle that corresponded with the direction of flow had the best results. On the other hand, the channels inclined by the same angle as the channels of older aerator had the worst efficiency. The decrease of aerator efficiency was caused by the large vortexes in the stator channels. and Obsahuje seznam literatury a názvosloví
Modelling of supercritical turbulent flow in an open channel with transversal ribs on its bottom was concentrated particularly on the development of flow separation behind ribs and on the corresponding changes of free surface. Further, the pressure drag of individual ribs was investigated including its dependence on the rib spacing, as well as the origin of secondary flow near the side walls of the channel behind ribs. Numerical results obtained by the software ANSYS CFX 11,0 were compared with experiments carried out by means of LDA and PTV techniques in free-surface water experiments carrid out by means of LDA and PIV techniques in free-surface water channel 200 x 200 mm with one or two transversal ribs 10 x 10 mm with various spacing. and Obsahuje seznam literatury
Heat generation in the cutting zone occurs as a result of the work done in metal cutting. In this study, in order to measure the temperature generated in the chip-forming zone, numerous experiments were carried out for different cutting regimes. During these experiments, the chip's top temperature was measured using an infrared camera. Collected data were analyzed, and temperature dependence on various cutting regimes was formulated. After that, measured data were modelled using the various techniques: response surface methodology, various types of artificial neural networks and neuro-fuzzy system. The accuracy of the proposed models is presented as well as their suitability for the considered problem. Finally, the system for the adaptive control of the cutting temperature, based on the proposed models, is presented.
The article provides a method of mathematical modelling of the dynamic properties of the electric locomotive wheelset drive. The linkage of the traction motor by means of the rotor pinion gear with the gear of wheelset drive is considered. The impact of couplings and operation conditions on the dynamic properties is studied. The method of decompositon into subsystems is applied for derivation of mathematical model of an interconnected system. This model is used for the calculation of modal values and also for investigating the forced vibration excited by pulsation moments of the asynchronous traction motor. The method is applied to a particular drive of the locomotive SKODA 109E. and Obsahuje seznam literatury
a1_Shallow ponds with rapidly photosynthesising cyanobacteria or eukaryotic algae are used for growing biotechnology feedstock and have been proposed for biofuel production but a credible model to predict the productivity of a column of phytoplankton in such ponds is lacking. Oxygen electrodes and Pulse Amplitude Modulation (PAM) fluorometer technology were used to measure gross photosynthesis (PG) vs. irradiance (E) curves (PG vs. E curves) in Chlorella (chlorophyta), Dunaliella salina (chlorophyta) and Phaeodactylum (bacillariophyta). PG vs. E curves were fitted to the waiting-in-line function [PG = (PGmax × E/Eopt) × exp(1 — E/Eopt)]. Attenuation of incident light with depth could then be used to model PG vs. E curves to describe PG vs. depth in pond cultures of uniformly distributed planktonic algae. Respiratory data (by
O2-electrode) allowed net photosynthesis (PN) of algal ponds to be modelled with depth. Photoinhibition of photosynthesis at the pond surface reduced PN of the water column. Calculated optimum depths for the algal ponds were: Phaeodactylum, 63 mm; Dunaliella, 71 mm and Chlorella, 87 mm. Irradiance at this depth is ≈ 5 to 10 μmol m-2 s-1 photosynthetic photon flux density (PPFD). This knowledge can then be used to optimise the pond depth. The total net P N [μmol(O2) m-2 s-1] were: Chlorella, ≈ 12.6 ± 0.76; Dunaliella, ≈ 6.5 ± 0.41; Phaeodactylum ≈ 6.1 ± 0.35. Snell’s and Fresnel’s laws were used to correct irradiance for reflection and refraction and thus estimate the time course of PN over the course of a day taking into account respiration during the day and at night. The optimum PN of a pond adjusted to be of optimal depth (0.1-0.5 m) should be approximately constant because increasing the cell density will proportionally reduce the optimum depth of the pond and vice versa., a2_Net photosynthesis for an optimised pond located at the tropic of Cancer would be [in t(C) ha-1 y-1]: Chlorella, ≈ 14.1 ± 0.66; Dunaliella, ≈ 5.48 ± 0.39; Phaeodactylum, ≈ 6.58 ± 0.42 but such calculations do not take weather, such as cloud cover, and temperature, into account., R. J. Ritchie, A. W. D. Larkum., and Obsahuje bibliografii a dodatky
Irradiance data software developed by the NREL Solar Radiation Laboratory (Simple Model of Atmospheric Radiative Transfer of Sunshine, SMARTS) has been used for modelling photosynthesis. Spectra and total irradiance were expressed in terms of quanta [mol m-2 s-1, photosynthetic photon flux density, PPFD (400-700 nm)]. Using the SMARTS software it is possible to (1) calculate the solar spectrum for a planar surface for any given solar elevation angle, allowing for the attenuating effects of the atmosphere on extraterrestrial irradiance at each wavelength in the 400-700 nm range and for the thickness of atmosphere the light must pass through during the course of a day, (2) calculate PPFD vs. solar time for any latitude and date and (3) estimate total daily irradiance for any latitude and date and hence calculate the total photon irradiance for a whole year or for a growing season. Models of photosynthetic activity vs. PPFD are discussed. Gross photosynthesis (Pg) vs. photosynthetic photon flux density (PPFD) (Pg vs. I) characteristics of single leaves compared to that of a canopy of leaves are different. It is shown that that the optimum irradiance for a leaf (Iopt) is the half-saturation irradiance for a battery of leaves in series. A C3 plant, with leaves having an optimum photosynthetic rate at 700 μmol m-2 s-1 PPFD, was used as a realistic worked example. The model gives good estimates of gross photosynthesis (Pg) for a given date and latitude. Seasonal and annual estimates of Pg can be made. Taking cloudiness into account, the model predicts maximum Pg rates of about 10 g(C) m-2 d-1, which is close to the maximum reported Pg experimental measurements. and R. J. Ritchie.
Helminth parasites of wild and domestic felines pose a direct or potential threat to human health. Since helminths depend on multiple environmental factors that make their transmission possible, it is imperative to predict the areas where these parasites may complete the transmission to potential hosts. Bobcats, Lynx rufus (Schreberer), are the most abundant and widely-distributed wild felid species in North America. The increase of population densities of bobcats raises concerns about their importance as reservoirs of pathogens and parasites that may affect wildlife, domestic animals and humans. Our objective was to predict the potential presence of the tapeworm Taenia rileyi Loewen, 1929, the fluke Alaria marcianae (La Rue, 1917) and the roundworm Toxocara cati (Schrank, 1788) in southern Illinois. The empirical presence of these parasites in localities across the region was analysed in combination with a sampling bias layer (i.e. bobcat presence) and with environmental data: layers of water, soil, land cover, human density and climate variables in MAXENT to create maps of potential presence for these three species in an area of 46 436 km2. All climatic variables were low contributors (0.0-2.0% contribution to model creation) whereas land cover surfaced as an important variable for the presence of A. marcianae (7.6%) and T. cati (6.3%); human density (4.8%) was of secondary importance for T. rileyi. Variables of importance likely represent habitat requirements necessary for the completion of parasite life cycles. Larger areas of potential presence were found for the feline specialist T. rileyi (85%) while potential presence was less likely for A. marcianae (73%), a parasite that requires multiple aquatic intermediate hosts. This study provides information to wildlife biologists and health officials regarding the potential impacts of growing bobcat populations in combination with complex and changing environmental factors.